Think in the language you are learning

As a fluent speaker of 4 languages, I have learned French and Italian the traditional way, i.e., in a class room setting at an age where (alas) a child's natural learning ability has almost vanished.

One experience I have been able to draw on from the languages I speak fluently is that when learning a language as an adult, one often thinks of a phrase in one's primary language and then translates it mentally into the language one wants to speak. This slows down speaking and generally leads to frustration, because as adults, we tend to form complex sentences that we are usually not capable of translating mentally on the fly without looking at a dictionary.

For this reason, avoid thinking in your own language. Only speak in a new language what you can form directly in your mind. You will then reach the point where speaking becomes a reflex instead of something you have to think about first. As you acquire proficiency in this way, you can gradually start to experiment with more complex sentence structures and learn new words to add to your sentences.

Coincidentally with this approach, I strongly recommend that you read comic books in the language you are learning. Don't start out with an adult book just because you're an adult. One of the reason children have an easy time learning languages is because at age 6-10 their regularly spoken vocabulary is probably around 500-600 words using simple grammatical structures. Comic books are written for readers within a similar age bracket, so you will be able to read faster and learn colloquial phrases at the same time. Once you can read a Donald Duck, Superman or Asterix comic book without a dictionary, then move on to adult books.